Ashwin’s career has grown by leaps and bounds in the last two years, sidelining other options to become Team India’s main spinner and a matchwinner both at home and away from it.

On the third day of the final Test between India and New Zealand at Indore, Ashwin claimed his 20th five-wicket haul during his spell of 6-81 that pushed the visitors on the backfoot. He’s already taken 20 wickets in the series, the most by any bowler from either side.

In the process, Ashwin became the third fastest to reach the 20 five-wicket haul landmark, behind Sydney Barnes from England and Clarrie Grimmett from Australia. He has played just 39 Tests.

"The change in Ashwin's bowling was first seen during India's 2014-15 tour of Australia. He benefited a great deal from Ravi Shastri being the team director," Gavaskar said, while speaking to NDTV.

Ravi Shastri took over as Team India’s director after India’s 1-3 Test series loss on their tour to England in 2014.

MS Dhoni, then India’s captain in all three formats, retired from Tests on India’s tour to Australia, Shastri’s second tour at the helm. Kohli then took over as the Test captain, and formed a strong rapport with the Director as India went on to win Test series against Sri Lanka and South Africa last year after their semi-final loss in the World Cup last year. They also claimed the Test series against West Indies 2-0 earlier this year.

Ashwin, whose spell against New Zealand took him past Ishant Sharma’s tally of 209 Test wickets, now stands fourth in the list of Indian bowlers with the most five-wicket hauls in Tests. Anil Kumble leads the list with 35 fIve-wicket hauls to his credit.

Gavaskar also stated that the revival came during India's tour to Australia in 2014, where Ashwin learned a thing or two from Nathan Lyon. "Before the Australian tour, Ashwin usually bowled on middle and leg. But looking at Nathan Lyon, he began bowling outside the off-stump," he said.

After reaching the landmark, Ashwin spoke about the support of other bowlers and the need of finding rhythm. "I look to get a five-for, as a batsman looks to get a hundred. You also need the help of other bowlers not to pick up wickets to get five-fors as often as I do. I don't find my rhythm very quickly in any of these spells in this series. Once I settled in, the body starts going into the ball, and that was one of those spells. Got to give credit to the way Rahane is pulling off those catches, staying low,” he said.